Additives for silicone oils



ZAQFAW DETS FOR SEKCONE &8

ayward R. Baker, Mount inier, Md and William A. Zlsman, Washington, D.0., ass ore to the United States of? America as represented by theSecretary oi the Navy No Drawing. Application r Se No. 8313M 4 ClasiCll.252-49.8)

(Gted under the act of March 3. 1888, as amended April 30, 1928; 370 Q.G. 757) This invention relates to anti-corrosion addi- A tives for usewith silicone oils, and to these oils containing the same.

In the efifort to find more nearly ideal lubricants than the petroleumhydrocarbons, especially in respect of inilammability, and alsoviscosity at low temperatures, a new type of oil, or series of oils, hasbeen developed wherein silicon plays an important part in the molecularstructure. These oils, briefly, are polymers of various organic siliconderivatives, such as the alkyl silicon halides, and they are known asthe silicone oils.

In spite of their unusual physical properties, these oils, bythemselves, are rather limited in application because they arerelatively corrosive when compared with the best protected hydro- 7carbon oils.

This invention provides a group of organic compounds which are solubleand compatible with the silicone oils at high and low tempera= tures andwhich inhibit the corrosive action of the oils when dissolved therein insmall quantities. The invention also includes these oils containing theanti-corrosion additives referred to. as new compositions of matter.

Not all organic compounds which are soluble in these oils are capable ofinhibiting their corrosive action. The group of the compounds which areeffective may be classified generally in the form ofseveral sub-groups,namely: naphthenic acids having molecular weights between about 180 andabout 400, metal naphthenates of these acids, and derivatives ofsaturated and unsaturated aliphatic hydrocarbons having chains of to 18carbon atoms. the derivatives being chosen from the group ofunsubstituted amines monocarboxylic acid derivatives, metal and aminesoaps of said monocarboxylic acid derivatives, aryl, chloraryl, alkaryland hydroaryl substituted monocarboxylic acid derivatives.

Typical, preferred compounds within these groups are described more indetail as follows:

The aliphatic series of acids from capric to palmitic protects steelfrom corrosion when in a mixture of silicone oil and water. However,larger quantities of the shorter chain acids are required to give thesame protection as the longer chain ones. All of this series arerecommended for temperatures above 0 F. except palmitic acid '2 which issuitable for temperatures above 32 F.

Unsaturated acids like stearolic acid, 9-octadecynolc acid, are suitableif usediat temperatures above 0 F., as are related acids of theunsaturated group with less carbon atoms.

Substituted aliphatic acids including chlorophenyl, benzyl, xylyl, tolyland naphthyl substituted aliphatic acids up to the stearic acidderivative are suitable corrosion inhibitors for use at temperatures notlower than minus 20 F.

Tetrahydronaphthyl stearic acid and related hydrogen substituted phenyl,xylyl and tolyl substituted aliphatic acids are recommended for use overthe temperature range of about minus 40 F. to about F.

Ethylphenyl stearic acid and related compounds from methyl to octadecyl,phenyl, benzyl, tolyl, xylyl and naphthyl substituted aliphatic acidsfrom capric to stearic acid are excellent anti-corrosion additives foruse at temperatures not lower than about 0 F. for the long chaincompounds to as low as minus 40 F. for the shorter chain compounds.

Aromatic substituted aliphatic acids, such as phenyl undecylic acid andxylyl undecylic acid, are satisfactory additives at temperatures as lowas minus 40 F., and their related acids such as I the phenyl. benzyl,tolyl, xylyl and naphthyl substituted aliphatic acids are also useful.The shorter chain acids are most useful at low temperatures, and thelonger chain ones at temperatures down to about0 F.

Naphthenic acids having molecular weights between about 188 and 400 haveproven very effective at both high temperatures and at temperaturesbelow minus 40 F.

The aliphatic amines from dodecyl to octodecyl amine are satisfactorydown to about 0 F.

Metal naphthenates, such as compounds of aluminum, nickel and manganese,inhibit corrosion but are not soluble in the silicone oils much below 32F. Other compounds suitable for use above about 32 F. includetrihydroxyethylamine stearate and metallic soaps such as zinc myristate,magnesium stearate, tin stearate and copper oleate.

Mixtures of any of these additives may be used in the silicone oils toachieve characteristics dependent on more than one type of additive.

A comparison of the eflects of difierent specific additives on siliconeoils is shown in the following table, the meaning of the abbreviationsbeing given below.

4 as a corrosion inhibitor, from about 0.1% to about 2.0% by weight of afatty acid having from about 10 to about 18 carbon atoms in its chain.

Corro- Percent Effect of Cold Silicone Solubility in Additive sionAdditiv btorage i112 oil used Rating by weight Silicone Oil weeks Caprlcacid 60%3-3 D. C 0.5 51 cl 0 F. Lam-lo acid" 60-3-4 D. O 2 0. 1 s1 cl 0F. M rlstic acid 00-3-3 D. C 1 0. I si cl 0 F. Pn. mitic acid... 60-3-3D. O-.. 0 0.2 sl cl 32 F. HLoarollc acid 60-3-2 D. C-.. H 0. 2 cl 010 F.Chlorophenyl steoric acid 60-3-3 D. C. 0 0.1 s] cl 20 F. ii thylphcnylstcnric acid 0-39 G. E. 0 0.3 :1 cl 0 F. 'loiruhydronaphthyl stem-i0 acl60-3-3 D. C 0 0.6 s -40). Phcnyl umiccyllc a 60-3-1 D. C 0 0.3 s 40g..\yl vl undccylic acid 00-3-2 D. O-.. 16 0.2 s -40 Naphthcnic acid M. W.240. 60-3-1 D. C 56 0.3 8 --40). Nuphthcnic acid M. W. 188, 60-3-1 D. C1s 0.3 S 40). n hvvuivcyi amine 00-3-1 D. C... i 0.2 sl cl-0 F. \lnm'uumnnphthcnate 60-3-3 D. 0.- 2 0.02 s1 cl 32 F. Niiliiii nnpllthcnate60-3-1 D. C it 0.1 i32 F. Manganese nnphthennte 00-3-3 D. lie 0. 2 s1010 F. 'lrillydroxycthylamine stearate 60-3-3 D. C 0 0.2 p. 132 F. Zincmyristata 00-3-3 D. C 2 0. 1 100 C sl cl 0 F. Magnesium stearata 60-3-1D. C it 0. l p. a. 100 C 132 F. 'liu stearate 60-3-3 D. 0.. 0 0. 2 p 8.100 C 132 F. Copper olcate 60-3-3 D. 0... M0 0.2 p s 100 l32 F.

s=soluhlc; i-insoluble s1 cl slightly cloudy p. s.=purtly soluble Thecorrosion rating was determined by a modification of the A. S. T. M.turbine corrosion test D-665-42T. The modification consisted of using aflat bottom Pyrex cylindrical container 80 by 18 mm. in size. Thespecimen was a piece of cold rolled steel 4.25 by 0.25 by 0.03 inch insize. The specimen'was attached directly to the shaft of a motor andserved as its own stirrer, revolving at approximately 1080 R. P. M. Thelower 1.78 inches of the specimen is the only part considered in thetest as it alone is in contact with the liquid sample. The sampleconsists of 9 parts by volume of silicone oil, 1 part of distilled Watercontaining the additive compound. thus giving a mixture of 90% siliconeoil and about 10% water. The steel specimen was rotated in the mixturefor 48 hours at 140 F.

Many variations will be apparent to those skilled in the art, and theinvention should not be limited other than as defined by the appendedclaims.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

We claim:

1. A hydraulic and lubricating fluid composition comprising essentiallya silicone fluid and from about 0.1% to about 2.0% by Weight of acorrosion inhibiting compound selected from the group consisting offatty acids, chloroaryl substituted fatty acids, alkaryl substitutedfatty acids and. hydroaryl substituted fatty acids wherein the fattyacid chain contains from about 10 to about 18 carbon atoms.

2. A hydraulic and lubricating fluid composition comprising essentiallya silicone fluid and,

D. C.=-Dow Corning G. E.=Gencral Electric ,3. A hydraulic andlubricating fluid composition comprising essentially a silicone fluidand, as a corrosionanhibitor, from about 0.1% to about 2.0% by weight ofan alkaryl substituted fatty acid having from about 10 to about 18carbon atoms in its chain.

4. A hydraulic and lubricating fluid composition comprising essentiallya silicone fluid and, as a corrosion inhibitor, from about 0.1% to about2.0% by weight of a chloroaryl substituted fatty acid having from about10 to about 18 carbon atoms in its chain.

HAYWARD R. BAKER. WILLIAM A. ZISMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date- OTHER REFERENCES Dow CorningFluids, bulletin by Dow Corning Corporation, Midland, Mich., 8 pages.Feb. 17. 1945.

The American Magazine. Oct. 1942, page 149.

